Switched local area networks use a network switch for supplying data frames between network stations, where each network station is connected to the network switch by a media. The switched local area network architecture uses a media access control (MAC) enabling a network interface card to access the media. The network switch passes data frames received from a transmitting station to a destination station based on the header information in the received data frame.
Networks typically will include a management agent that monitors activity by a hub or repeater. The management agent may include analysis and/or diagnostic equipment and may be concerned with statistical information related to the network in order to identify how well a network is being utilized. Such statistical information may include what types of packets are on the network, what protocols are being used on the network, the packet sender identity, the packet receiver identity, and the distribution of the of the packet lengths being transferred on the network.
Network repeaters will typically send management information to the management agent on a MAC layer protocol. For example, commonly-assigned U.S. Pat. No. 5,592,486 discloses a repeater that compares a destination address of a received data packet with a destination address corresponding to a management unit address. The data packet is compressed if its destination address does not match the stored management unit address, where transmission of the data packet to the management unit is halted once the counted number of bytes matches a predetermined number. A valid frame check sequence (FCS) is then provided at the end of the compressed data packet following transmission of the received data packet.
Commonly-assigned U.S. Pat. No. 5,550,803 also provides a MAC-layer transmission of received data packets to a management unit, where the data portion of a received data packet is transferred by a repeater to a management unit. Statistical information is then appended to the data portion following transmission of the received data packet during an interpacket gap interval.
The above-disclosed arrangements are beneficial for network systems having repeater devices, since a repeater device has a shared medium with all network devices, requiring transmission of a single data packet at a time under Ethernet (IEEE 802.3) protocol. Switched network architectures using a network switch, however, are configured for simultaneously transmitting and receiving a plurality of data packets on network ports serving respective network stations. Hence, the technique of halting transmission of a received data packet after a prescribed number of bytes, followed by appending additional data after complete reception of the received data packet results in wasted bandwidth during the idle time between halted transmission and the appended additional data. Moreover, this technique does not contemplate multiple data packets simultaneously received by a network switch. Appending the statistical information at the end of the data packet also requires the management agent to wait until the entire packet is received before determining the nature of the data packet (i.e., why the data packet was received). Finally, the statistical information tagged (i.e., appended) to the end of the data packet generally includes only statistics related to the actual received data packet.